vacuum pump?
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vacuum pump?
1984 F250 w/6.9 The brake pedal pushes half way and will not return. If the brakes are used a second time the pedal is harder to push and braking is not nearly as effective. If the pedal is pulled back up to the normal height (I put my boot under the pedal and pull it back up) prior to pushing pedal again, brakes work fine I have had problems with the brakes in many ways from lines rusted and leaking to leaking calipers. This truck does not get a lot of use. and typically check the master cylinder fluid level before driving and found the master cylinder low of fluid and refilled but never found a leak. That was several months ago and not sure if it would be related in any way.
The fluid in the master cylinder is always very muddy looking and have tryied to flush it but find it stays very muddy. Because this truck was used as a farm truck, it stayed covered with mud, cow manure and other contaminants like liquid nitrogen and such. I have considered replacing every line and the master cylinder just to get unrusted and clean components in order to better see if and where leaks are.Just not sure if the pedal problem should go all the way to the vacuum pump or power booster even.
The fluid in the master cylinder is always very muddy looking and have tryied to flush it but find it stays very muddy. Because this truck was used as a farm truck, it stayed covered with mud, cow manure and other contaminants like liquid nitrogen and such. I have considered replacing every line and the master cylinder just to get unrusted and clean components in order to better see if and where leaks are.Just not sure if the pedal problem should go all the way to the vacuum pump or power booster even.
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From: Angier, NC
On the low master level is it the one closest to the booster or both?
I would say the master is leaking into the booster and has been damage.
I think I would rebuild / replace everything in the brake system starting with master / booster, all lines, wheel cly and calipers then you know everything is new and when filled with fresh fluid you should get clean fluid at all wheels.
In the rebuild of my truck I replaced the wheel cly., calipers, rubber hoses, drained all the lines and sucked all the mud out of the master.
It still took a lot of fluid to get clean fluid at each wheel.
BTW after all that I found the parts truck (a roll over so was on the road) master & booster bad so need to replace them at some point.
Dave ----
I would say the master is leaking into the booster and has been damage.
I think I would rebuild / replace everything in the brake system starting with master / booster, all lines, wheel cly and calipers then you know everything is new and when filled with fresh fluid you should get clean fluid at all wheels.
In the rebuild of my truck I replaced the wheel cly., calipers, rubber hoses, drained all the lines and sucked all the mud out of the master.
It still took a lot of fluid to get clean fluid at each wheel.
BTW after all that I found the parts truck (a roll over so was on the road) master & booster bad so need to replace them at some point.
Dave ----
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From: Virginia
That looks like a project. I would replace the booster and the master, and plan on replacing a lot of the lines also. You can get universal lines at the store in different lengths, The nuts on the lines that thread into the master are usually non-standard size for the line, so you can try to save them when they twist off the line, or sometimes you can use a brass adapter they sell in the store to make the standard size fitting fit.
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That looks like a project. I would replace the booster and the master, and plan on replacing a lot of the lines also. You can get universal lines at the store in different lengths, The nuts on the lines that thread into the master are usually non-standard size for the line, so you can try to save them when they twist off the line, or sometimes you can use a brass adapter they sell in the store to make the standard size fitting fit.
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From: Virginia
All the fittings at the 4 wheels use the standard ones that come already on the lines. The only oddball one is sometimes the tee mounted on the rearend housing with the hose made onto it. I have used a brass adapter for that before also. If you go to replace the line running along the frame to the rear, I suggest you use at least 3 lines and two couplers. I have done this on several vehicles, I usually get a fairly long line and run it along the frame behind the gas tank where you do not have very good access, and then on the front beyond the tank run a coupler and a shorter piece forward and up to the master cylinder or the proportioning valve, and do the same for the rear portion of the line from the back part of the tank to the rearend hose mount.
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Yes, the lines along frame to rear end were partially replaced a few years ago. I will replace from MC down to proportioning valve and go from there with new lines and hoses anywhere they are old. Removing the power booster will be a challenge judging by the condition of the studs. I will start soaking this with penetrating fluid.
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From: Angier, NC
Yes, the lines along frame to rear end were partially replaced a few years ago. I will replace from MC down to proportioning valve and go from there with new lines and hoses anywhere they are old. Removing the power booster will be a challenge judging by the condition of the studs. I will start soaking this with penetrating fluid.
You do not have to undo the master from the booster as the new one should come bolted together.
Dave ----
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When you talk about replacing lines and using couplers you are just referring to a male to male coupler in order to connect the female nut on lines together.
I have some flaring tools that I have used on other equipment for making lines and recall there are different attachments for different flares. It may be necessary to cut and flare in order to get the lines connected without excess tubing bent into loops to make line length correct.
It may be a good time to clean and inspect the proportioning valve if I am taking lines loose from it. I will not open it up unless there are obvious problems as I do not want to have to buy one as they aren’t cheap and possibly even hard to find.
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From: Angier, NC
Yes master & booster as1 complete unit, at least for most cars & trucks.
If you have the flaring tool with the dies for different size tubing and you are going to replace all the brake lines I would look into a coil of cooper / nickel tubing and maybe a few of the fittings for the ends so you don't have to reuse the old ones.
Some times for the master they use a different size fitting for the same tube size and they can be hard to come by so you may have to reuse that one.
Now because you are using a coil of tubing you would not need couplers to join 2 lines together. Just run 1 long line front to back.
Then use what is left to make the shorter lines.
If you need more tubing you should not need much and you can then get a shorter line from the store to finish the job.
As for that valve it might good to pull it apart for a good cleaning and look over.
What shape are the wheel cly. and calipers in? if replacing everything else may also be best to replace them as well so you know the brake system is 100% good.
Dave ----
If you have the flaring tool with the dies for different size tubing and you are going to replace all the brake lines I would look into a coil of cooper / nickel tubing and maybe a few of the fittings for the ends so you don't have to reuse the old ones.
Some times for the master they use a different size fitting for the same tube size and they can be hard to come by so you may have to reuse that one.
Now because you are using a coil of tubing you would not need couplers to join 2 lines together. Just run 1 long line front to back.
Then use what is left to make the shorter lines.
If you need more tubing you should not need much and you can then get a shorter line from the store to finish the job.
As for that valve it might good to pull it apart for a good cleaning and look over.
What shape are the wheel cly. and calipers in? if replacing everything else may also be best to replace them as well so you know the brake system is 100% good.
Dave ----
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From: Virginia
I always use the pre-made lines you can get in the store. I have never had a problem with way too much line. I recommend you get the line a little bit long, when you bend it by hand your bends have more radius to them to prevent kinking the line, so this takes up some extra line. If you need to zig-zag the line a little bit in a couple of places it does no harm. I have started using the copper nickel lines they sell, this stuff is great. It doesn't rust, and it runs and bends like copper wire, very easy to do.
The couplers are female flare on both sides. Don't let the guy in the store give you a pipe coupler, you need the coupler with the flare seat in both ends.
You can flare the lines yourself, you may have to at the master cylinder to re-use those fittings. Not sure how much flaring you have done, but the automotive lines require a double flare. Your flaring kit will need to have the double flare dies in it. Double flaring is a little tricky and requires a couple of times before you get the hang of it, so don't be discouraged if you don't get a good flare the first time or two.
The couplers are female flare on both sides. Don't let the guy in the store give you a pipe coupler, you need the coupler with the flare seat in both ends.
You can flare the lines yourself, you may have to at the master cylinder to re-use those fittings. Not sure how much flaring you have done, but the automotive lines require a double flare. Your flaring kit will need to have the double flare dies in it. Double flaring is a little tricky and requires a couple of times before you get the hang of it, so don't be discouraged if you don't get a good flare the first time or two.
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You can replace the master separately from the booster on the F-250 with the 6.9l. However if the master leaked into the booster you probably want to change it out too. Looks like this truck has been run in an area where they like to use liquid deicer on the road. The master and booster are rusted up pretty good so I'd probably replace them both. I really like being able to stop my truck.